15 basic knowledge that injection mold must know


1. Nozzle The melt usually flows from the nozzle into t […]

1. Nozzle
The melt usually flows from the nozzle into the sprue, but in some molds, the nozzle is part of the mold because it extends to the bottom of the mold. There are also two main types of nozzles: open nozzles and closed nozzles. In injection molding production, open nozzles should be used more because they are less expensive and less likely to hold up.
2. Filter and Combined Nozzle
3. Exhaust
Here, the gas can be expelled from the holes or holes in the shot cylinder. Then the diameter of the screw root is increased, and the melted glue of volatiles is adapted to the nozzle. Injection molding machines equipped with this facility are called vented injection molding machines. There should be a good smoke exhauster with catalytic burner above this exhaust injection molding machine to remove potentially harmful gases.
To get a high-quality melt, the plastic is heated or melted consistently and mixed well. Proper melting and mixing requires the correct screw and sufficient pressure (or back pressure) in the shot cylinder for mixing and thermal consistency.
4. Stop valve
5. Screw back (reverse cable)
6. Screw gasket
7. Rotation speed of screw
8. Shot quantity
9. Plasticizing ability
10. Estimation of plasticizing capacity
11.Residence time of injection cylinder
The actual residence time can be determined by experiment by measuring the time required for the colored plastic to pass through the injection cylinder, which can be roughly calculated by the following formula: t=(Rated material volume of injection cylinder gX Cycle time S)÷(Injection cylinder Quantity gX300) Please note that some plastics will stay in the shot tank longer than the calculated time because they can agglomerate in the shot tank.
As a general practice, the residence time of a plastic on a particular injection molding machine should be calculated. Especially when the large injection molding machine uses a small shot size, the plastic is easily decomposed, which is not detectable from observation. If the residence time is short, the plastic will not be plasticized uniformly; if the residence time is long, the plastic properties will be attenuated.
12. shot cylinder temperature environment
The temperature in the other zones is then gradually increased until it reaches the nozzle, which tends to be slightly cooler at the tip of the nozzle to prevent dripping. The mold is also heated and cooled, and the molds are also divided due to the size relationship of many molds, but unless otherwise stated, each area should be set to the same size
It can be measured by the nozzle or by the air jet method. When measuring with the latter, care must be taken to ensure that the hot melt is not accidentally cleaned, as the high temperature of the hot melt can burn or even corrode the skin. In the injection molding workshop, burns are accidental.
13. Mold temperature
14. even cooling
15. Temperature and Cooling Checks
Always check that the injection molding machine is set and running at the temperature specified on the log. this is very important. Because temperature affects the surface finish and yield of injection molded parts. All measured values ​​must be recorded and the injection molding machine checked at the specified time.

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